Cal. RTC § 6202

(a) Every person storing, using, or otherwise consuming in this state tangible personal property purchased from a retailer is liable for the tax. His or her liability is not extinguished until the tax has been paid to this state except that a receipt from a retailer engaged in business in this state or from a retailer who is authorized by the board, under the rules and regulations as it may prescribe, to collect the tax and who is, for the purposes of this part relating to the use tax, regarded as a retailer engaged in business in this state, given to the purchaser pursuant to Section 6203, is sufficient to relieve the purchaser from further liability for the tax to which the receipt refers.

(b) Notwithstanding any other provision, when a person purchases a vessel or aircraft from another person through a broker, the purchaser’s liability for use tax is relieved if the purchaser has paid an amount as sales or use tax to the broker, and the purchaser obtains and retains a receipt from the broker showing the payment of that tax to the broker.

(c) Notwithstanding any other provision, when a person purchases a vessel or aircraft from another person through a broker, if the broker collects from the purchaser an amount as sales or use tax, the broker shall be liable for that amount under Section 6204 as if the broker were a retailer engaged in business in this state required to collect that amount as use tax from the purchaser, and that amount constitutes a debt owed by the broker to this state.